Conventional batch type plants for producing asphaltic mix typically comprise a drum dryer for heating and drying the stone aggregate, and a vertical bucket elevator for conveying the heated and dried aggregate from the dryer to the top of a tower. The tower includes an enclosed vibrating screen section at the top, for receiving and segregating the aggregate by size. The segregated aggregate then drops through individual chutes to a bin section which underlies the screen section, and which comprises a plurality of separate bins, and so that each bin receives an aggregate of a predetermined average size from the screen section. A weigh hopper is positioned below the bins, which permits the aggregate from one or more bins to be weighed out to provide a desired mixture, as required for example for a roadway base coat or a finish coat. A mixing pugmill is positioned below the weigh hopper for mixing the weighed quantity of aggregate with hot liquid asphalt, and the bottom of the pugmill includes a gate opening, such that the contents may be dropped into an underlying truck.
It is desirable to locate the asphalt plant as near as possible to the point of use, in order to minimize trucking expense. However, it often is not possible to locate the plant as near to the point of use as would be desirable. For example, conventional plants often generate dust and contribute to air pollution, and they may be noisy. As a result, many localities will not issue the necessary permits. Also, the projected asphalt production may not justify the expense of a conventional plant, or the space may be too limited or too expensive to justify a plant.
It is accordingly an object of the present invention to provide a method and apparatus for producing asphaltic mix and which avoids or at least minimizes the above noted problems associated with conventional plants.
It is a more specific object of the present invention to provide a method and apparatus of the described type and which utilizes a satellite plant which has a low environmental impact, which is relatively small in size and cost, and which can be profitably located at sites which are impractical for conventional plants.